Does hyperbaric oxygen enhance the effect of photodynamic therapy in patients with advanced esophageal carcinoma? A clinical pilot study

Background and Study Aims: Experimental studies have shown that the cytotox icity of porphyrins and related substances is mediated mainly by singlet ox ygen and that hypoxic cells are less affected by porphyrins and light. In a clinical pilot study we assessed the use of photodynamic therapy (PDT) und er hyperbaric oxygen (HBO), compared with PDT under normobaric conditions, in patients with advanced esophageal carcinoma. Patients and Methods: After diagnostic work-up and staging, photosensitizat ion in all patients was carried out using hematoporphyrine derivate (HpD) ( 2 mg/kg bodyweight 48 hours prior to PDT). We then applied light at 630 nm (KTP-Nd:YAG laser with DYE box) at dose of 300J/cm, delivered by a fiber wi th a radial light-diffusing cylinder (length 1 cm), inserted through the bi opsy channel of the endoscope, Of the patients, 14 (12 with stage III cance rs, and two with stage TV cancers) were treated by PDT alone, and 17 patien ts (15 with stage III cancers, and two with stage IV cancers) received PDT under HBO at a level of 2 absolute atmospheric pressures (ATA). Transcutane ous PO2 levels of 500-750 mmHg under HBO, compared with transcutaneous PO2 levels of 60-75 mmHg under normobaric conditions, were measured. Results: Improvements regarding dysphagia and stenosis diameter were obtain ed in both treatment arms with no significant differences (P = 0.36 and 0.1 4, respectively). The tumor length also decreased in both groups and showed a significant difference in favour of the PDT/HBO group (P = 0.002). Kapla n-Meier statistics showed median overall survival for the PDT group and the PDT/HBO group as 7.0 and 12 months respectively. The 12-month survival I a te was 28.6% for the PDT group and 41.2% for the PDT/HBO group. Logrank tes t showed a difference in survival in favor of the PDT/HBO group (P = 0.059) . No major treatment-related complication occurred, and the 30-day mortalit y rate was 0%. Conclusions: Combined PDT/HBO 1 represents a new approach in the treatment of esophageal cancer which, in this pilot study, appears to have enhanced t he efficiency of PDT.